The ideal arrangement for a fibre reinforced metal ring, or disc, is to arrange the fibres circumferentially such that they extend continuously without breaks in a fully dense metal matrix. This is difficult to achieve because a certain amount of movement is required in practice to achieve good diffusion bonding, and density, between the layers of fibres. The fibres used to reinforce the metal matrix are ceramic, and ceramic fibres have very low extension to failure values, typically 1%. On consolidation using radial pressure from the inside surface of the ring the continuous ceramic fibres are placed under high tensile stress resulting in fibre breakage and loss of structural integrity. On consolidation using radial pressure from the outer surface of the ring the continuous ceramic fibres are buckled which reduces structural integrity. On consolidation using radial pressure from both the inside and outside surfaces of the ring the continuous ceramic fibres either break under high tensile stress for the radially inner layers of ceramic fibres or buckle for the radially outer layers of ceramic fibres. This resulting fibre reinforced metal ring therefore contains many random fibre breaks and thus the fibre reinforced metal ring has unknown levels of mechanical properties.
In one known method of manufacturing a fibre reinforced metal ring, as disclosed in UK patent application No. GB2168032A, a filament is wound spirally in a plane with a matrix metal spiral between the turns of the fibre spiral. The fibre spiral and matrix metal spiral are positioned between discs of matrix metal, and is then pressed axially to consolidate the ring structure. This produces little or no breaking of the fibres.
In a further known method of manufacturing a fibre reinforced metal ring, as disclosed in UK patent application No. GB2070833A, a metal matrix tape, which has reinforcing fibres, is wound onto a mandrel and then inserted into a metal shaft. The fibres are arranged to extend generally axially of the shaft. The assembly is pressed to consolidate the ring structure. This method does not have the ideal arrangement of fibres for a ring.
Another known method of manufacturing a fibre reinforce metal ring, as disclosed in UK patent application No. GB2198675A, a continuous helical tape of fibres and a continuous helical tape of metal foil are interleaved. The interleaved helical tapes of fibres and metal foil are placed in an annular groove in a metal member and a metal ring is placed on top of the interleaved helical tapes of fibres and metal foil. The metal ring is pressed axially to consolidate the assembly and to diffusion bond the metal ring, the metal member and the interleaved helical tapes of fibres and metal foil together to form an integral assembly. This method produces little or no breaking of the fibres. This method requires the use of a vacuum chamber and a hot press and die.